Trends in Highway Use

North Carolina is one of a handful of states that have no county highway departments.  Those roadways in about 45 of the states that are maintained by county highway departments are instead a part of the state-maintained system in the Tarheel State, where they are called “secondary roads.”  The North Carolina Highway Department (NCDOT) took over all county roads in the 1930s, in order to have greater leverage with vendors and suppliers of the materials necessary to more economically build and maintain highways. 

Currently, with over 78,000 miles of state-owned and maintained highways, North Carolina has one of the two largest state-owned and maintained highway systems in the country.  In North Carolina, municipalities maintain an additional 18,000 miles of city streets, and combining these two administrative systems with highways maintained by other agencies such as the National Park Service or the U.S. Forest Service, the state contains  approximately 100,000 miles of roads and highways.  Ferry crossings of several rivers and sounds connect links of the highway system in many coastal counties. Ferries are operated by the State Ferry Division, also in the NC Department of Transportation.  The State Highway System is shown in Figure 1.

One statistic used frequently as a measure of highway usage is Vehicle Miles Traveled (VMT), usually expressed on a daily or annual basis. VMT is not an actual measure, however.  Daily VMTs on individual segments of both state-maintained highways and municipal streets are typically estimated by periodic or continuous traffic counts.  On an annual basis, a statewide estimate of VMT for each county is a combination of these site-specific traffic counts and an estimate developed by the North Carolina Department of Revenue based on tax collections from motor vehicle fuel sales; the size and composition of the vehicle fleets, both public and private; and averages of miles per gallon for various types of vehicles.  Trends in VMT on individual highway segments, by county, and for the state as a whole, are therefore useful as a measure of the growth of highway travel over time. 

Comparing VMT for 1995 and 2003 (Figures 2 and 3), most counties in the state experienced rather large percentage increases in  (Figure 4).  Note that in Figures 2 and 3, miles traveled are shown as units of 100 Million Vehicle Miles Traveled (or 100MVMT).   For example, 1995 data show (Figure 2)  that Alamance County experienced between 2.0 and 4.0 hundred million vehicle miles traveled that year.  The actual estimate that Alamance experienced was 292 Million VMT in 1995.  In 2003, Alamance County had 357 Million VMT, and the legend shows, again, between 2.0 and 4.0 hundred million VMT.  Figure 4 shows that county with a 20.0 and 29.9 percent increase from 1995 to 2003; the actual percent change was 22.3 percent.   

Sixteen of the state’s one hundred counties experienced a 30 percent or more increase in VMT during this eight year period. Most of these counties with larger increases were in rural regions.  However, an additional 73 counties experienced between 10 and 30 percent change in VMT between 1995 and 2003.  Only eleven counties experienced less than a 10 percent change.  All of the counties in the latter group are rural counties in the mountain or coastal regions of the state.  Overall, these increases suggest both good news and not so good.  On the positive side, a healthy economy is reflected in these numbers. On the other hand, the highway system, particularly in the larger urban areas, is experiencing increasing congestion, increasing commuting time, accompanying traffic safety issues, air and water quality issues, and higher public demand for highway improvements. 

One might obtain more insight into the cause of the growth in Vehicle Miles Traveled by comparing counties in Figure 4 with Figures 4a and 4b in the NC Atlas web site chapter on Population. 

As Table 1 indicates, between 1995 and 2000, total rural and urban public road length increased by 3,004 miles.  While this is a rather large number, on the statewide scale, this equates to an insignificant  increase in actual highway mileage inventory during any given year.  The largest increase in new roadway mileage was additional “local” roads on both the state’s urban and rural systems.  A few miles of Interstate highways were added in some of the years, and these small increases in the centerline miles of major highways has added significant congestion relief to local residents and commuters.  These miles increased do not include additional lane miles, such as when two-lane highways are widened to three, four or five lanes.  Mileage shown in Table 1 reflects roads, streets and highways maintained by all agencies (State, municipal, Federal park and forest roads, etc.). 

Table 2 illustrates that the majority of the state’s public roads are owned by the North Carolina Department of Transportation (NCDOT), representing 78% of the state’s total.  Municipalities within the state own and maintain another 18.5% of the state’s total. 

Table 3 relates various growth measures from 1980 through 2001 (the latest year that all these measures are commonly available).  Note that the number of licensed drivers and VMT increased at a much higher rate than  did vehicle registrations.  Table 4 and Figure 5 illustrate a one year “snapshot” of the number of vehicles by type that were registered in the state in the year 2000.

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